v0.31.1 - 2019-02-15

Features 🌈

• built new VHD image including Kubernetes 1.10.13 ([#514])
• enable configurable containerd version (#516)
• add support for private Azure container registry / custom hyperkube image during provisioning (#523) and ([#526])

Please report any issues here: https://github.com/Azure/aks-engine/issues/new